First Observation of the B ¯ s0 → Λc+ Λ ¯ c- Decay and Evidence for the B ¯ 0 → Λc+ Λ ¯ c- Decay

LHCb Collaboration

doi:10.1103/cxn3-8t4g

First Observation of the B ¯ s0 → Λc+ Λ ¯ c- Decay and Evidence for the B ¯ 0 → Λc+ Λ ¯ c- Decay

LHCb Collaboration

Science Park 105
University of Warwick
Physik-Institut der Universität Zürich
University of Liverpool
Syracuse University
Universidade de Santiago de Compostela
University of Bristol
University of Glasgow
Uppsala University
Université Paris-Saclay
University of Michigan, Ann Arbor
Clermont-Auvergne University
Agh University of Science and Technology Faculty of Computer Science
LNF-INFN
University of Dortmund
Lamarr Institute for Machine Learning and Artificial Intelligence
University of Freiburg
Vilnius University
European Organization for Nuclear Research
University of Cambridge
Sorbonne Université
Instituto de Biofisica da UFRJ
State Key Laboratory of Nuclear Physics and Technology
Istituto Nazionale di Fisica Nucleare, Sezione di Firenze
Sezione INFN di Ferrara
Universidade da Coruña
INFN Sezione di Milano-Bicocca
University of Milano-Bicocca
University of Chinese Academy of Sciences
INFN Roma Tor Vergata
Consejo Nacional de Rectores (CONARE)
Aix-Marseille Université
ENAC-IIC-GEL
Massachusetts Institute of Technology
Ip Paris
University of Oxford
University of Heidelberg
Ruhr-University Bochum
Centro Brasileiro de Pesquisas Fisicas
Pontifícia Universidade Católica do Rio de Janeiro
University of Manchester
INFN Sezione di Bologna
University of Edinburgh
Institute of High Energy Physics, Chinese Academy of Sciences
Eötvös Loránd University
Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
Sezione di Genova
Sezione di Roma
Universitat Ramon LLull - CSIC
INFN
National University of Kyiv
University Bonn
Imperial College London
Laboratoire de Physique des Particules
University of Modena and Reggio Emilia
University of Victoria
MST-8, Los Alamos National Laboratory
Maastricht University
University of Ferrara
Monash University
Institute for Nuclear Physics
Tadeusz Kosciuszko Cracow University of Technology
The Ohio State University
Sezione INFN di Cagliari
Tsinghua University
Wuhan University
University of Barcelona
University of Campinas (UNICAMP)
University of Bologna
University of Genoa
Scuola Normale Superiore di Pisa
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University of Milano
Institute of Nuclear Research, National Academy of Sciences in Ukraine
Horia Hulubei National Institute of Physics and Nuclear Engineering
INFN Sezione di Bari
University of Cincinnati
Universidad Nacional Autónoma de Honduras
Central China Normal University
Hunan University
Universitá di Cagliari
ICS/University of Groningen
Centro Federal De Educacão Tecnológica Celso Suckow Da Fonseca
Università degli studi di Bari Aldo Moro
University College Dublin
South China Normal University
INFN Sezione di Perugia
CCLRC Rutherford Appleton Laboratory
University of Perugia
University of Valencia
University of Maryland, College Park
Kharkov Institute of Physics and Technology
National Centre for Nuclear Research (NCBJ)
RWTH Aachen University
Universidad Nacional de Colombia
Institute of Physics of the Czech Academy of Sciences
University of Birmingham
Vrije Universiteit Amsterdam
University of Pisa
Henan Normal University
Lanzhou University
University of Padova
Dipartimento di Fisica
Universidad de Ingeniería y Tecnología (UTEC)
University of Siena
Max-Planck-Institut für Kernphysik
Universidad de Alcalá
University of Urbino Carlo Bo
Universidad Andres Bello

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Abstract

A search is presented for the two-body charmed baryonic decays, B¯(s)0→Λc+Λ¯c-, using a data sample collected by the LHCb experiment during 2011-2012 and 2015-2018, corresponding to an integrated luminosity of 9 fb-1. The first observation of the B¯s0→Λc+Λ¯c- decay is reported with 6.2σ significance along with 4.3σ evidence for the B¯0→Λc+Λ¯c- decay. The branching fractions are measured to be B(B¯0→Λc+Λ¯c-)=(1.01-0.28+0.27±0.08±0.15)×10-5 and B(B¯s0→Λc+Λ¯c-)=(5.0±1.3±0.5±0.8)×10-5, where the first uncertainty is statistical, the second systematic, and the third due to external inputs. These results provide novel experimental inputs for the theoretical framework describing two-body baryonic decays of B mesons via W-emission and W-exchange mechanisms.

Original language	English
Article number	061802
Journal	Physical Review Letters
Volume	136
Issue number	6
DOIs	https://doi.org/10.1103/cxn3-8t4g
Publication status	Published - 13 Feb 2026

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@article{6d6c7ff2d1b54dd8b71c1bd30dc0d3b4,

title = "First Observation of the B ¯ s0 → Λc+ Λ ¯ c- Decay and Evidence for the B ¯ 0 → Λc+ Λ ¯ c- Decay",

abstract = "A search is presented for the two-body charmed baryonic decays, B¯(s)0→Λc+Λ¯c-, using a data sample collected by the LHCb experiment during 2011-2012 and 2015-2018, corresponding to an integrated luminosity of 9 fb-1. The first observation of the B¯s0→Λc+Λ¯c- decay is reported with 6.2σ significance along with 4.3σ evidence for the B¯0→Λc+Λ¯c- decay. The branching fractions are measured to be B(B¯0→Λc+Λ¯c-)=(1.01-0.28+0.27±0.08±0.15)×10-5 and B(B¯s0→Λc+Λ¯c-)=(5.0±1.3±0.5±0.8)×10-5, where the first uncertainty is statistical, the second systematic, and the third due to external inputs. These results provide novel experimental inputs for the theoretical framework describing two-body baryonic decays of B mesons via W-emission and W-exchange mechanisms.",

author = "\{LHCb Collaboration\} and R. Aaij and Abdelmotteleb, \{A. S.W.\} and \{Abellan Beteta\}, C. and F. Abudin{\'e}n and T. Ackernley and Adefisoye, \{A. A.\} and B. Adeva and M. Adinolfi and P. Adlarson and C. Agapopoulou and Aidala, \{C. A.\} and Z. Ajaltouni and S. Akar and K. Akiba and M. Akthar and P. Albicocco and J. Albrecht and R. Aleksiejunas and F. Alessio and \{Alvarez Cartelle\}, P. and R. Amalric and S. Amato and Amey, \{J. L.\} and Y. Amhis and L. An and L. Anderlini and M. Andersson and P. Andreola and M. Andreotti and \{Andres Estrada\}, S. and A. Anelli and D. Ao and C. Arata and F. Archilli and Z. Areg and M. Argenton and \{Arguedas Cuendis\}, S. and L. Arnone and A. Artamonov and M. Artuso and E. Aslanides and \{Ata{\'i}de Da Silva\}, R. and M. Atzeni and B. Audurier and Authier, \{J. A.\} and D. Bacher and \{Bachiller Perea\}, I. and V. Balagura and F. Fleuret and E. Maurice",

note = "Publisher Copyright: {\textcopyright} 2026 CERN, for the LHCb Collaboration. Published by the American Physical Society under the terms of the {"}https://creativecommons.org/licenses/by/4.0/{"}Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP",

year = "2026",

month = feb,

day = "13",

doi = "10.1103/cxn3-8t4g",

language = "English",

volume = "136",

journal = "Physical Review Letters",

issn = "0031-9007",

number = "6",

}

TY - JOUR

T1 - First Observation of the B ¯ s0 → Λc+ Λ ¯ c- Decay and Evidence for the B ¯ 0 → Λc+ Λ ¯ c- Decay

AU - LHCb Collaboration

AU - Aaij, R.

AU - Abdelmotteleb, A. S.W.

AU - Abellan Beteta, C.

AU - Abudinén, F.

AU - Ackernley, T.

AU - Adefisoye, A. A.

AU - Adeva, B.

AU - Adinolfi, M.

AU - Adlarson, P.

AU - Agapopoulou, C.

AU - Aidala, C. A.

AU - Ajaltouni, Z.

AU - Akar, S.

AU - Akiba, K.

AU - Akthar, M.

AU - Albicocco, P.

AU - Albrecht, J.

AU - Aleksiejunas, R.

AU - Alessio, F.

AU - Alvarez Cartelle, P.

AU - Amalric, R.

AU - Amato, S.

AU - Amey, J. L.

AU - Amhis, Y.

AU - An, L.

AU - Anderlini, L.

AU - Andersson, M.

AU - Andreola, P.

AU - Andreotti, M.

AU - Andres Estrada, S.

AU - Anelli, A.

AU - Ao, D.

AU - Arata, C.

AU - Archilli, F.

AU - Areg, Z.

AU - Argenton, M.

AU - Arguedas Cuendis, S.

AU - Arnone, L.

AU - Artamonov, A.

AU - Artuso, M.

AU - Aslanides, E.

AU - Ataíde Da Silva, R.

AU - Atzeni, M.

AU - Audurier, B.

AU - Authier, J. A.

AU - Bacher, D.

AU - Bachiller Perea, I.

AU - Balagura, V.

AU - Fleuret, F.

AU - Maurice, E.

N1 - Publisher Copyright: © 2026 CERN, for the LHCb Collaboration. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP

PY - 2026/2/13

Y1 - 2026/2/13

N2 - A search is presented for the two-body charmed baryonic decays, B¯(s)0→Λc+Λ¯c-, using a data sample collected by the LHCb experiment during 2011-2012 and 2015-2018, corresponding to an integrated luminosity of 9 fb-1. The first observation of the B¯s0→Λc+Λ¯c- decay is reported with 6.2σ significance along with 4.3σ evidence for the B¯0→Λc+Λ¯c- decay. The branching fractions are measured to be B(B¯0→Λc+Λ¯c-)=(1.01-0.28+0.27±0.08±0.15)×10-5 and B(B¯s0→Λc+Λ¯c-)=(5.0±1.3±0.5±0.8)×10-5, where the first uncertainty is statistical, the second systematic, and the third due to external inputs. These results provide novel experimental inputs for the theoretical framework describing two-body baryonic decays of B mesons via W-emission and W-exchange mechanisms.

AB - A search is presented for the two-body charmed baryonic decays, B¯(s)0→Λc+Λ¯c-, using a data sample collected by the LHCb experiment during 2011-2012 and 2015-2018, corresponding to an integrated luminosity of 9 fb-1. The first observation of the B¯s0→Λc+Λ¯c- decay is reported with 6.2σ significance along with 4.3σ evidence for the B¯0→Λc+Λ¯c- decay. The branching fractions are measured to be B(B¯0→Λc+Λ¯c-)=(1.01-0.28+0.27±0.08±0.15)×10-5 and B(B¯s0→Λc+Λ¯c-)=(5.0±1.3±0.5±0.8)×10-5, where the first uncertainty is statistical, the second systematic, and the third due to external inputs. These results provide novel experimental inputs for the theoretical framework describing two-body baryonic decays of B mesons via W-emission and W-exchange mechanisms.

UR - https://www.scopus.com/pages/publications/105030332981

U2 - 10.1103/cxn3-8t4g

DO - 10.1103/cxn3-8t4g

M3 - Article

AN - SCOPUS:105030332981

SN - 0031-9007

VL - 136

JO - Physical Review Letters

JF - Physical Review Letters

IS - 6

M1 - 061802

ER -

First Observation of the B ¯ s0 → Λc+ Λ ¯ c- Decay and Evidence for the B ¯ 0 → Λc+ Λ ¯ c- Decay

Abstract

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